Method of making aqueous loaded latex compositions

Abstract

Method of making aqueous dispersions of hydrophobic polymer particles loaded with at least one hydrophobic compound, comprising the consecutive steps of dissolving said at least one hydrophobic compound in a water-immiscible organic solvent medium, dispersing the solution obtained in water or in an aqueous medium to form a dispersed phase having an average droplet size lower than 5 μm, mixing the resulting dispersion with a dispersion of hydrophobic polymer particles in water or in an aqueous medium, said hydrophobic polymer particles being swellable in said water-immiscible solvent medium and having an average particle diameter ranging from 0.02 to 5.0 μm, stirring the mixture obtained to allow said hydrophobic compound to associate with said hydrophobic polymer particles, and removing said water-immiscible organic solvent medium by evaporation.

We claim: 
     
       1. Method of making aqueous dispersions of polymer particles loaded with at least one hydrophobic compound for subsequent use, comprising the consecutive steps of: dissolving said at least one non-polymeric hydrophobic compound in a water-immiscible organic solvent medium,   dispersing the solution obtained of said at least one non-polymeric hydrophobic compound in water or in an aqueous medium to form a dispersed phase having an average droplet size lower than 5 μm,   mixing the resulting dispersion of said at least one hydrophobic compound with a dispersion of polymer particles in water or in an aqueous medium, said polymer particles being swellable in said water-immiscible solvent medium and having an average particle diameter ranging from 0.02 to 5.0 μm,   stirring the mixture obtained to allow said non-polymeric hydrophobic compound to associate with said polymer particles, and   removing said water-immiscible organic solvent medium by evaporation to provide an aqueous dispersion for said subsequent use.   
     
     
       2. A method according to claim 1, wherein said hydrophobic compound is a dye, an optical brightener, an UV-absorbing agent, a spectral sensitizer, a polymerizable compound, or a photoinitiator. 
     
     
       3. A method according to claim 1, wherein said dispersion of polymer particles in water or in an aqueous medium is a dispersion of homopolymers or copolymers of acrylic acid, methacrylic acid, and salt or esters thereof, styrene, and mixtures of these, a dispersion of polymethyl methacrylate, a dispersion of polystyrene, a dispersion of co(ethyl acrylate/stearyl methacrylate), or a dispersion of co(methacrylic acid/methyl methacrylate/stearyl methacrylate). 
     
     
       4. A method according to claim 1, wherein said polymer particles have an average particle diameter ranging from 0.2 to 4.6 μm. 
     
     
       5. A method according to claim 1, wherein the weight ratio of said hydrophobic compound to said polymer particles ranges from about 1:10 to 1:2. 
     
     
       6. A method according to claim 1, wherein said polymer particles of the dispersion are alkali-soluble polymer particles. 
     
     
       7. A method according to claim 1, wherein said water-immiscible organic solvent is ethyl acetate, methylene chloride, or a mixture thereof.